3rd generation partnership project (3GPP) long term evolution (LTE) is an improved version of a universal mobile telecommunication system (UMTS) and is introduced as the 3GPP release 8. The 3GPP LTE uses orthogonal frequency division multiple access (OFDMA) in a downlink, and uses single carrier-frequency division multiple access (SC-FDMA) in an uplink. The 3GPP LTE employs multiple input multiple output (MIMO) having up to four antennas. In recent years, there is an ongoing discussion on 3GPP LTE-advanced (LTE-A) that is an evolution of the 3GPP LTE.
A micro cell, a femto cell, and a pico cell, etc., having a small service area can be installed in a specific location of a macro cell having a wide coverage. Such a network environment is called a heterogeneous network.
In a heterogeneous network environment, an actual UE speed is not significantly increased. However, due to the presence of cells having a small coverage such as a pico cell and a femto cell, the number of times of performing mobility of the UE may be significantly increased. Accordingly, a phenomenon may occur in which a mobility state obtained as a result of mobility state estimation (MSE) cannot properly consider an actual UE mobility state.
Since the UE performs mobility on the basis of the estimated mobility state, if the mobility state is not properly estimated, mobility may be performed not properly. Since this causes a situation in which the UE receives a service from a wrong cell, quality of overall network services and efficiency of provided service may deteriorate.
Accordingly, there is a need for a method capable of performing MSE by properly considering the actual UE mobility state and a method of supporting mobility of the UE to allow the UE to properly perform mobility in a wireless communication environment such as a heterogeneous network.